1. Field of the Invention
The invention relates to moldable resin compositions and molded articles obtained therefrom.
The invention relates in particular to blow moldable resin compositions based on polyether ester elastomers or block copolymers in which rubber like polyether soft segments and plastic like hard segments are alternately linked to one another.
2. Description of the Related Art
The blow molding of polyesters in particular polyether ester elastomers is known, but remains problematic especially for the blow molding of very long parts which requires specific rheological properties, in particular a closely controlled high melt strength to avoid unwanted sagging.
U.S. Pat. No. 4,010,222 reports that the addition of a copolymer containing polymerized ethylene units and polymerized carboxylic acid units to a copolyester elastomer improves its processing by blow molding.
U.S. Pat. No. 4,912,167 describes a blow moldable composition of a polyester such as polybutylene terephthalate (PBT), polyethylene terephthalate (PET) or a PBT/PET blend, an epoxide polymer and a source of catalytic ions.
U.S. Pat. No. 5,128,404 describes a blow moldable composition containing polybutylene terephthalate, an ethylene copolymer containing epoxide groups and an ionomer obtained by partially neutralizing with Na+ of K+ the carboxyl groups of an ethylene copolymer containing (meth)acrylic acid.
U.S. Pat. No. 5,523,135 describes the problems of blow molding thermoplastic polyester resins, and reports an improvement for a combination of a thermoplastic polyester resin, typically, PBT, with a styrenic copolymer. In Comparative Example 12 it reports that blow molding was impossible when the PBT was replaced with a PBT-containing polyester ether elastomer.
EP-A-0,577,508 aimed to improve the blow moldability of polyether ester elastomers (block copolymers) which hitherto were not considered suitable for blow molding, by mixing them with an epoxy compound and a phenol alkali metal salt.
Canadian Patent Application 2,039,132 proposed a general improvement in polyether ester elastomers (block copolymers) by mixing them with an aromatic thermoplastic polyester, like PBT, PET or blends thereof, a rubbery interpolymer and optionally a mineral filler.
Whereas certain polyether ester elastomer formulations have been successfully used for blow molding, it still remains problematic to provide a blow moldable resin composition based on polyether ester resin that has a high parison stability, with little tendency to sag, for the blow molding of very long parts, especially for sequential co-extrusion or 3-D parison manipulation techniques.